Studies on the CNS-availability of amphetamine from amphetaminil

The biotransformation of amphetaminil to amphetamine was confirmed using 3H- and 14C-labelled ampehtaminil. The metabolites were isolated, identified and quantified from blood, brain, adipose tissue and urine. These studies showed that the intact molecule of amphetaminil passes into the circulation only to a very small extent. The time spent by the amphetaminil in the alimentary canal does not appear to be a critical factor in the stability and degradation of this substance. The proportion of unchanged amphetaminil represents no more than 2% of the total radioactivity in the blood. The amphetamine, which results from the cleavage of amphetaminil, enters the CNS and is excreted in the urine after hydroxylation and glucuronidation. The other cleavage product, benzaldehyde, seems to be rapidly converted into hippuric acid, which is excreted. Amphetaminil is enriched in adipose tissue, especially after i.p. injection; but this fraction will be cleaved upon re-entering the blood, and it can only enter the brain as amphetamine.